The paper is aimed to utilize pyrolysed oil (PO) as a fuel candidate in a direct injection diesel engine. Concentrated solar energy was used to produce pyrolysed oil from Jatropha biomass. The pyrolysed oil was upgraded and blended with diesel at 20%, 40%, and 60% shares (PODB20, PODB40, and PODB60). Experimental tests were conducted on a 3.7 kW single cylinder compression ignition (CI) engine at different loads with base diesel and PO blended fuels. Experimental results showed the improvement in thermal efficiency of the engine with low percentage of PO shares (PODB20 and PODB40) as compared to base diesel however, it was decreased slightly with high percentage of PO share (PODB60). In cylinder pressure was increased initially with addition of PO until 40% due to the dominant effect of inherent oxygen content, and then declined with further addition of PO due to the dominant effect of lower heating value and higher density of PO. Ignition delay and combustion duration were increased continually with increasing percentage of PO share. Unburnt hydrocarbons, carbon monoxide and smoke emissions initially decreased with lower PO shares (20% and 40%) due to high combustion temperature and later increased with higher PO share (60%), whereas oxides of nitrogen emission was followed the reverse trends. A clear insight obtained from the study is that blending of PO with diesel to a certain extent (until 40%) is beneficial in terms of higher thermal efficiency and lower emissions (all carbon based emissions) beyond which a slight penalty in the engine performance and emission characteristics was explored. (C) 2017 Elsevier Ltd. All rights reserved.